Key Laboratory of Biotechnology and Crop Quality Improvement of the Ministry of Agriculture of China, Biotechnology Research Center, Southwest University, Chongqing 400716, People's Republic of China.
Appl Environ Microbiol. 2010 Jan;76(1):254-63. doi: 10.1128/AEM.00882-09. Epub 2009 Oct 23.
Beauveria bassiana is an important entomopathogenic fungus widely used as a biological agent to control insect pests. A gene (B. bassiana JEN1 [BbJEN1]) homologous to JEN1 encoding a carboxylate transporter in Saccharomyces cerevisiae was identified in a B. bassiana transfer DNA (T-DNA) insertional mutant. Disruption of the gene decreased the carboxylate contents in hyphae, while increasing the conidial yield. However, overexpression of this transporter resulted in significant increases in carboxylates and decreased the conidial yield. BbJEN1 was strongly induced by insect cuticles and highly expressed in the hyphae penetrating insect cuticles not in hyphal bodies, suggesting that this gene is involved in the early stage of pathogenesis of B. bassiana. The bioassay results indicated that disruption of BbJEN1 significantly reduced the virulence of B. bassiana to aphids. Compared to the wild type, DeltaBbJEN1 alkalinized the insect cuticle to a reduced extent. The alkalinization of the cuticle is a physiological signal triggering the production of pathogenicity. Therefore, we identified a new factor influencing virulence, which is responsible for the alkalinization of the insect cuticle and the initiation of fungal pathogenesis in insects.
球孢白僵菌是一种重要的昆虫病原真菌，被广泛用作生物防治剂来控制害虫。在球孢白僵菌转移 DNA（T-DNA）插入突变体中，鉴定出一个与酿酒酵母 JEN1 编码的羧酸转运蛋白同源的基因（B. bassiana JEN1 [BbJEN1]）。该基因的破坏降低了菌丝中的羧酸含量，而增加了分生孢子的产量。然而，该转运蛋白的过表达导致羧酸含量显著增加，分生孢子产量降低。BbJEN1 强烈诱导昆虫外骨骼，并在穿透昆虫外骨骼的菌丝中高度表达，而不在菌丝体内表达，这表明该基因参与了球孢白僵菌致病的早期阶段。生物测定结果表明，破坏 BbJEN1 显著降低了球孢白僵菌对蚜虫的毒力。与野生型相比，DeltaBbJEN1 使昆虫外骨骼碱化的程度降低。外骨骼的碱化是触发致病性产生的生理信号。因此，我们鉴定出了一个影响毒力的新因子，该因子负责昆虫外骨骼的碱化以及真菌在昆虫中致病性的启动。
